A generator set (genset) includes a combination of a generator and a prime mover, for example a combustion engine. As a mixture of fuel and air is burned within the engine, a mechanical rotation is created that drives the generator to produce electrical power. Ideally, the engine drives the generator continuously with a relatively constant torque and speed, and the generator accordingly produces an electrical power output having relatively constant characteristics (frequency, voltage, etc.).
Gensets can be used as a backup or a sole source of power. For example, a primary source of power such as a utility grid is typically connected to supply a load with power for critical use, for example, to supply a hospital or a manufacturing facility with power. When the primary source of power fails, the genset is brought online to provide backup power for the critical use. And, when the primary source of power is reconnected to supply power for the critical use, the genset is shutdown. In another example, a genset can be used as the only source of power such as in a manufacturing facility or at a worksite remote from utility power. In these situations, the genset may be operated for extended periods of time such as during a work shift, and then shut down during the night; used at night, and then shut down during the day; or used only during a particular time of the year.
As either a backup or primary source of power, a genset can sit in a shutdown condition for extended periods of time between operations. During this time, the genset may cool undesirably. If started and immediately ramped to full operation in this condition, accelerated wear may occur as a result of the cooling. Thus, a means for warming the genset in preparation for operation or maintaining warmth of the genset between operations may be desired to extend the life of the genset.
An exemplary system for warming a genset is described in U.S. Pat. No. 5,198,698 (the '698 patent) issued to Paul et al. on Mar. 30, 1993. Specifically, the '698 patent discloses an auxiliary power supply system that includes an internal combustion engine driving an alternator to provide electrical power to DC bus lines, across which a storage battery is connected. When a voltage across the bus lines drops below a selected value, the engine is turned on for a period of time to warm it up, during which time the power from the generator is not supplied to the DC bus lines. The time during which the engine is running without power being delivered from the generator is selected to allow the engine to warm up to a desired operating temperature before it is fully loaded.
Although the system of the '698 patent may be helpful in warming a genset under certain conditions, it may be less than optimal. That is, the system may not have the appropriate controls, alarms, and shutdown triggers required to properly protect the genset under varying conditions, or the ability to override these mechanisms during the warmup time period. Further, the system of the '698 patent may not provide for operation in the warmup mode during extended periods of time when power from the genset is not required.